Rock wool mass



Aug. 29, 1950 N. K. CHANEY ETAL ROCK WOOL MASS Filed March 20, 1946 Patented Aug. 29, 1950 252,124

ROCK WOOL M'A SS Newcomb K. Chaney, Moylan, and Claude W. J ordain, Pali, Pa., assignorsto UnitedGas Improvement Company, acorporation of Pennsylvania Application March 20, 1946, Serial No. 655,774

4 Claims.

This invention pertains to new rock wool masses.

7 This. invention pertains more articularly to the reprocessing of rock wool as ordinarily producedto make a new rock wool masshaving fiber diameters falling within a selected range orranges considerably narrower than is 'found in ordinary rock wool, and having fiber lengths falling within'a selected range or ranges and con siderably shorter than is found in ordinary rock greatStpr0b1emS met with by the Industry WOOL overtne last or years, and particularly s nce The invention pertains more particularly to automatic gas f a an of which reqmt'e the production of rock wool masses having sesmal pllot flame have come mto lected' fiber diameters and lengths and which are r more genelzal P Vt t substantially free from mineral dust and beads U promefn of t p remely t e which are normally present in substantial pro- Yapor a gum particles f rom the gas pno'r to its passage through the extremely small valve portion in ordinary rock wool. t d b th f t th t The invention pertains still more particularly f 1s gleat y p e ac to the production of improved rock wool masses P'e'prebsure on the gas m we qh-stllbtltlgn maims 11, and at the appliance it is hardly to be used in the filtration from a gas-of extreme- )0 Very Sma n 1y minute suspended particles including particles morefthan 3 Inches of wtlter'column h t f, the 0 de f 1 ltisa well accepted rule in the industry that afvmg lame rm lmensmns 0 r any device calculated to remove the gum must mlqron h as.the exjiremely mmute not result in a pressure drop in the gas of more toxic particles occurring 1n toxic smokes used wanQn/edngh of Water column, and that Such for mmtary purposes a the i i mmilte device must remove all of the gum from the gas, Yapor Phas? gum particles ordmallly P E f since in the case of a certain widely used pilot m combustlble, gas prduc ed for dl-stnbutlon m burner, as little as 0.006025 gram of gum is suffif mains aha Vanously as town gas or cient to completely stop up its valve opening. clty It 15 also useful the removal It is also a well accepted rule in the industry from of 9 3 and of bacterlal c1ump of that any such device must have a reasonably long ultramicroscopic size, as well as o he pa s useful life without diminution of gas flow due to of'slmllar eXtremely mlnllte (11111911510115- collected gum, for otherwise, its failure would be It is l known that in m y instances Such merely substituted for that of the valve. combustible gas, for example, carburetted water Although extensive effgrts have been made to gas, or oil gas, orcoal gas, has unavoidably pressqlvecthis problem involv n ny diff re t ent omp n n which reac with ea h h r in preaches, including filtration and otherwise, the the v p p a to rm xtr m ly minute gum only successful and practicable solution of the particles which remain suspended in the gas, and problem cit which we are aware has been made are known collectively as vapor phase gum. In 40 by Mr. Wilton E. Stackhouse, and is'described typical cases, the number of gum particles may and claimed in copending application Serial be of the order of from 20,000 to 100,000 per cc. No. 301,678, filed October 28, 15239, now Patent The latter concentration is approximately 3,000,- No. 2,400,719 issue-:1 May 21, 1946. 090,000 particles per cubic foot. This solutioninvolves the filtration of thegum Many'of these particles are so small that they particles from the gas by passage of the gas cannot be observed even with the use of the: through-a rock wool filter mass falling within ultra-microscope. a. specified density range and having .certain Combustible gas, of the character described, is minimum depth specifications. used for many industrial and domestic purposes, Thefilter of said copending application is not such as, for burning in stoves, hotwater heaters, only capable of removing all of the vapor phase house heaters, refrigerators, and other appli gum from a combustible gas, but is also capable ances. Such use of the combustible gas commonof removing without undue pressure drop, other ly tinvolves burningof the gas-in what is known particles of similar minute dimensions from the in the art as a low ratev appliance burner of sameor any other gas, such as the removal from which theburner on a refrigeratorand the pilot air for breathing purposes of toxic smoke partilight burners on gas stoves, hot water heaters and house heaters, are examples.

The gas how to a low rate appliance burneris commonly regulated by a valve which has an extremely small opening. Unless the vapor phase gum is removed from the gas prior to its passing through such small valve opening, the gum will collect inthe opening to eventually stop it up and extinguish the burner. This has been one of the 3 cles of pollens and of bacterial clumps of ultramicroscopic size.

Our new and improved rock wool may be used in a rock wool filter of the character referred to above with improved results from the standpoint of a substantially greater permissible fiow of gas through a filter of given size or dimensions with complete filtration, and with a greater filter life expectancy.

In our new filter mass a certain percentage range of extremely fine rock wool fibers (but not too fine) and having high surface area relative to mass, are distributed upon and supported by a certain percentage range of coarser rock wool fibers (but not too coarse) of sufficient mechanical strength and resilience to provide our desired structural support and spatial distribution in the rock wool filter mass.

To obtain a filter mass in which the interstices between and formed by the fibers are more uniform as to size and spatial distribution, and in which the fibers are interlaced to a greater degree, we employ fiber lengths which are considerably shorter than the fiber lengths which usually occur in ordinary rock wool.

In accordance with our invention, we provide a new rock wool mass which is comprised of fibers which range in diameter approximately from 1 to 10 microns (expressed to the nearest 0.5 micron), and which preferably range in length approximately from 0.05 to 5 mm. As is well known, 1 mm. is equal to 1000 microns.

Referring now more particularly to fiber diameters, preferably, at least approximately 40% of the fibers present by numerical count have diameters falling in the range of approximately from 1 to 3.5 microns, and at least approximately 5% of the fibers present by numerical count have diameters falling in the range of approximately from 6 to 10 microns.

Excellent results are obtained when the numerical percentage of fibers falling in the diameter range of approximately from 1 to 3.5 microns is approximately from 50% to 85%, and when the numerical percentage of fibers falling in the diameter range of approximately from 6 microns to 10 microns is at least 5 Such results are further improved when the numerical percentage of fibers falling in the diameter range of approximately from 1 micron to 3.5 microns is approximately from 55% to 65%, and when the numerical percentage of fibers falling in the diameter range of approximately from 6 microns to 10 microns is at least approximately 5%, such as approximately from 5% to 25%.

When these preferred percentage range ratios of finer to coarser fibers obtain, then the numerical percentage of other fibers present in our new rock wool mass, that is, fibers having diameters which do not fall within either the diameter range of approximately from 1 micron to 3.5 microns or the diameter range of approximately from 6 to 10 microns, may vary approximately from 55% down to 0%. Such fibers obviously fall into a diameter range intermediate of those set forth above, that is, within a diameter range of approximately from 3.5 microns to 6 microns. The numerical percentage range of approximately from 55% to 0% for these fibers of intermediate diameter is, of course, narrowed to approximately from 45% to 0% and to approximately from 40% to 0% such as approximately from 40% to 10%, as the preferred percentage range ratios of finer fiber to coarser fiber become more specific as set forth above.

Referring now to fiber lengths, at least approximately and more preferably at least approximately numerically of said fibers of our new rock wool mass preferably, but not necessarily, fall within the above mentioned preferred range for fiber lengths of approximately from 0.5 mm. to approximately 5 mm., within which an intermediate range of approximately from 0.1 mm. to approximately 2 mm. is still more preferred. A differently stated preference is that fiber lengths are at least approximately 0.05 mm. and more preferably at least approximately 0.1 mm.

Our new rock wool mass is preferably composed substantially entirely of fibers falling within the above mentioned specifications stated generally, with the various degrees of preference given to the respective ranges or limits, as stated. However, we find that some allowance may be made for the possible presence of some of the undesired material present in ordinary rock wool, such as mineral dust, beads, extremely fine fiber, extremely short fiber, coarser fiber, longer fiber, etc. Accordingly, it may be stated that at least by weight, such as at least 98% by weight, of the total rock wool mass should be composed of fibers, and that at least 95% numerically, such as at least 98%, of said fibers should fall within the generic diameter specifications above given, and that at least 80%, and more preferably at least 85%, such as at least 95% numerically of said fibers should fall within the generic length specifications above given. Should the rock wool fibers be coated with a resinous material the approximate average composite diameter of the coated fiber is considered. In connection with weight specifications, the weight of the total coated material applies if the fibers are coated. If uncoated, the uncoated weight, of course, ap-

plies.

A fiber, for the purposes of this specification, is to be considered as an element having a length at least 10 times its diameter.

Our new rock wool mass may be prepared as follows:

Example 1 A rock wool blanket or other rock wool mass is separated such as with a pointed instrument until broken down into separate fibers or small fiber bundles. A quantity such as 10 grams of this separated material and say 200 times its weight of water are placed in a container with a variable speed short bladed motor driven propeller type stirrer, such as the more or less conventional soda fountain mixer, and mixed first at low speeds until the fibers are completely wetted, and then at high speed until any fiber bundles are broken up and the material is more or less uniformly dispersed in the water. This may take from 5 to 5 minutes depending upon the mixing capacity of the stirrer. After complete dispersion the beating is continued until the desired reduction in average fiber length has been obtained as determined by sampling from time to time. With efiicient beating this does not require as much time as the initial dispersion. The rapidity of dispersion and degree of fiber shortening may be increased by the insertion into the container out of the path of the propeller of a stationary knife edge ballle, slightly deflected from the direction of rotation to reduce the rotational speed of the suspension relative to the speed of the stirrer. The water suspension of fiber is now poured into a larger vessel containing say an equal volume of water, and the fiber kept in gentle agitation by stirrin atia rateg sufficient tQ: ke pli h-e.' fibnouse material in suspension, while:permittingtthe heavy beads andtcofarse aggregate *tOqCO'HeCtF-bn theefloor of the! vessel. The :suspension is :now;

decanted from; the heavy :settlingsinto a second .1

vessel, and-qtheg:gentleragitatiorr slS repeatedzuntil i substantial sedimentationPofanyzrema'ining non fibrcus beads;- ori heavyefibervaggregates ceases This.-;is;a-ol;lowedzby decantation or lthe suspension; as before, leaving the settlingssbehind This p'ro' cedure may; be repeated 'if andias; man-y .timesias,

thefihrou-s;materialssettlel without agitation for from oneftopsevera'l minutes,'.-thus leavingita. supernatant suspension 5 0f finely; div ided\ dust i particles andwerysshort andv or veryzfine fibers; which is removed by decanting Q'bhiSl-IPEDHQIEQYII suspension; The--fine=cdust iparticles and. very short and/onverycfinefiber have slower initial .1,

settling :rates' than the lo nger de'sired fiber, and I maywber-easi-ly ,=decanted therefrom. This"operationgiszrepeatedto remove any..-fines whi'chfm'ay have become 'entangled in and carried downwith the desired fiber:' This proceduremay be further repeated;if, and as -many. times as; nec' essar-mzin; casethere "is an excessive percentage of fiber in the range of 1 tc "3. 5; microns diameters" which it is? -desired to -remove-s Slight agitation, suchas-by stirring-,1 maybe resorted to, if nec'es-- sar-yi'or desirable; to; assist infloating or suspending fine fiber for" separation i purposes.

Agglomeratesfzor 'small bundles of fiber have higher: settling; rates than the I individual fibers; and while the accidental-formation cf sucl'r in or'e rapidly fallingabundles is continuously occurring throughout the suspension, the frequency'of such occurrencerisza: functionofv the dilution The greater theg dilution themore effective isth'esepa ration of: fines.

stages of decantation described above can be-= reversed, or under proper conditions carried on simultaneously; 7

The invention :may-Jbe' further illustrated gin connection'with th'e accompanying drawings in mannenacrossthe end of member "I as indicated 7 at 8. The screw plug is provided with the pas sage 9-=which -is shownwith threads at'IIJ, and which communicates with the filterchamber. I I andsl 2 arespidersprovidedwith rims as'shown at Bland-armsas-shown-at Mandare adapted to furnish support forscreens wand l6." I1 is a filterelement-of' rock W001; For-convenience;-

6- innassemblycand connection, ithe' m'emberci may be provided with I wrench r grips as: ShOWDTC'BJlEi'I and ithefhead sof the screw/plug 1 maysbetformed It as-a :nu-t:

Since=:the.--filter particularly. illustrated Land's.

described is:- desighed"- more-'aparticularly for 115G251" in'connection withra pilot: burneraon-l a fdom'esticfi gas stove; all metal partsaare preferably-ore inaterialor materialsl whichrdo. not corrode in the- :presence oi manufactured ga'sm As :an 2 example;-

thevfiltenchamberil the screw plug lian'd spi ders I I and i 2-=may;be .of brass which preferably hae-t a copper content not greater:.than68 and still more preferablwnot': substantially greater than 63% ,iandcscree'ns 1 I Stand i l 6 may 'be or stainless steel-i A l6 mesh 'screenis very:satisfactory; 'although othensuitable'mesh screen may be' em played;

The interior bore is preferablyaccurately-"(il mensioned in diameter and length as is also the screw plug. The screens -and-"spiders are preferably more or. less accuratelyiormed .insthickness. Such accurate-dimensioning facilitatesthe: securing of the: desired rock wool arrangementin- .assembling'the filter, as in such. casea -pre-de-- installation, efficiently filtered heavily gummed 5-, 6 toengage the'screwplug l which is' adapted tobescrewed into the bore-and'to fit in'gas tight? termined quantity "of "rock! woolI'may. be .merely. compressedto the desiredYcross-sectional area depth and density.

Inso assembling the filter the spider iil ism positioned against the seat Z andlthetscreennlt'i placed abuttingthe spider. A-weighed or other:- wise previouslydetermined quantity-ofrock aWOOl may be thenpla'cediri thefilter chamber. andthe screen 'I 6 "and spider. l2 fpositioned -on the other side'fof it. The sorewplugl is then=introduced and tightened 'until it fits..in .gas-tight contadt witlijthe end of member 1 asatl8,- compressing. the rock. wool within the chamber.

Accurate. dimensioning of 1 the parts predete-rminesthe cross-section, density anddepthof the-- other low rate gas consuming device.

In use, the gas flows through the filter, elementidepositing therein thegumparticles and other suspended solids, the screens and'spide'rs serving to-retainthe' rock woolwith'out"unduly 5 impeding the flow'of the gas;

The spider's with their arms Mserve to sup; port'the screens and-preventtheir bulging .while holding tlie filtermass in place and further'ser've i to--provide gas spaces for distributing .the gas 1 across the area of the-filter'element.

Example 2 A filter similar to-thatshowninFigure 1 hav-. in'g a cham'ber bore of 0.75 inch-in diameterandan overall-chamber lengthof 0.75inch', provided with a-screW-plug;screensand spiders dimen sioned to provide a space-for rock wool 0.50 inch depth; This filter was filled with 1.06"grams' of ounnew rock wool massand, after assembly and "proximately 4.80 gramsper cubicinchi- The rock wool filter element of Example 2 was substantially free from non-fibrous 'materials such as beads and mineral dust. The numerical percentage of fibers present having diameters within the range of from 1 to 3.5 microns was 44%, the numerical percentage of fibers present having diameters within the range of from 3.5 to 6 microns was 27%, the numerical percentage of fibers having diameters within the range of from 6 to microns was and the numerical percentage of fibers present having diameters greater than 10 microns was 4%, all figures being reasonable approximations.

Substantially all of the fibers present had lengths falling within the range of from 0.05 to 5 mm. with at least 90% numerically of the fibers present having lengths falling within the range of from 0.1 to 2 mm., all figures being reasonable approximations.

Example 3 A filter having the dimensions of the filter of Example 2 was filled with 0.68 gram of another embodiment of our new rock wool mass, and after assembly and test, was found capable of efiiciently filtering heavily gummed gas at a rate of 2.04 cubic feet of gas per hour at a pressure drop of 1 inch of water column across the filter. The density of the rock wool filter element was approximately 3.08 grams per cubic inch.

The rock wool filter mass of Example 3 had a numerical percentage of fibers having diameters within the range of from 1 to 3.5 microns of 83%, a numerical percentage of fibers having diameters falling in the range of from 3.5 to 6 microns of 8.5%, a numerical percentage of fibers having diameters falling in the range of from 6 to 10 microns of 8.5% and no fibers present having diameters greater than 10 microns, all figures being reasonable approximations. The filter mass was also substantially free from non-fibrous material such as beads and mineral dust. Substantially all of the fibers present had lengths falling within the range of from 0.05 to 5 mm.

with at least 90% numerically of the fibers present having lengths falling within the range of from 0.1 to 2 mm., all figures being reasonable approximations.

Example 4 A filter having the dimensions of the filters of Examples 2 and 3 was filled with 0.80 gram of another embodiment of my new rock wool mass and after assembly and test, was capable of efiiciently filtering heavily gummed gas at a rate of 2.37 cubic feet of gas per hour at a pressure drop of one inch of water column across the filter. The density of the rock wool was approximately 3.62 grams per cubic inch.

The numerical percentage of fibers present in the rock wool mass having diameters falling within the range of from 1 to 3.5 microns was 61%, the numerical percentage of fibers falling within the range of from 3.5 to 6 microns was 15%, the numerical percentage of fibers falling in the range of from 6 to 10 microns was 23%, and the numerical percentage of fibers having diameters of more than 10 microns was 1%, all figures being reasonable approximations.

Substantially all of the rock wool mass was fibrous in character and substantially all of the fibers had lengths falling within the range of from 0.05 to 5 mm. with at least 90% numerically of the fibers having lengths falling within the 8 range of from 0.1 to 2 mm., all figures being rea sonable approximations.

The density of rock wool when referred to herein and in the claims means apparent density as distinguished from absolute density, apparent density being equal to the weight in grams of a given fibrous mass divided by the volume in cubic inches of the space occupied by it. Because of variations within the material itself this density is obviously average.

The rock wool filter element may have any desired density suitable for the purpose, such as between 3 grams per cubic inch and 16 grams per cubic inch, and more particularly between 3 grams per cubic inch and 10 grams per cubic inch. The depth, density and cross-sectional area of the filter element are usually adjusted with respect to each other so that the desired filtration is obtained with the desired rate of flow. A filter mass depth of at least inch is usually preferred, for example, a depth of approximately inch.

While the invention has been more particularly described in connection with water as the elutriating medium, it is to be understood that any other suitable liquid medium may be substituted. Examples are preferably of low viscosity and low vapor pressure hydrocarbon oils such as kerosene, solvent naphthas, xylene, etc., higher boiling alcohols, and glycols, or their water solutions, ketones, esters, etc., and water solutions of soluble inorganic salts.

From the foregoing examples, the efliciency of our new rock wool mass for the removal of vapor phase gum becomes readily apparent. Our invention is likewise applicable to the removal from air of toxic smokes, of pollens, of bacterial clumps, as well as of other particles of ultramicroscopic dimensions,

Therefore, having more particularly described our invention, it is to be understood that this is by way of illustration, and that changes, omissions, additions, substitutions and/0r modifications may be made within the scope of the claims without departing from the spirit of the invention.

We claim:

1. A new rock wool mass at least 95% by weight of which is composed of fibres whose lengths are at least ten times their diameters, of which fibres at least approximately 40% numerically range in diameter approximately from 1 to 3.5 microns, at least approximately 5% numerically range in diameter approximately from 6 to 10 microns, and at least approximately 95% numerically range in diameter approximately from 1 to 10 microns.

2. A new rock wool mass at least 95% by weight of which is composed of fibres whose lengths are at least ten times their diameters, of which fibres at least approximately 40% numerically range in diameter approximately from 1 to 3.5 microns, at least approximately 5% numerically range in diameter approximately from 6 to 10 microns, at least approximately 95% numerically range in diameter approximately from 1 to 10 microns, and at approximately 95% numerically range in length approximately from 0.05 to 5 mm.

3. A new rock wool mass at least 95% by weight of which is composed of fibres whose lengths are at least ten times their diameters, of which fibres approximately from 50 to numerically range in diameter approximately from 1 to 3.5 microns, at least approximately 5% nuleast ten times their diameters, of which fibres approximately from to numerically range in diameter approximately from 1 to 3.5 microns, approximately from 5% to 25% numerically range in diameter approximately from 6 to 10 microns, at least approximately 98% numerically range in diameter approximately from 1 to 10 microns, at least approximately numerically range in length approximately from 0.1 to

2 mm., and at least approximately numerically range in length approximately from 0.05 to 5 mm.

NEWCOMB K. CHANEY. CLAUDE W. JORDAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,624,163 Dolbear et al. Apr. 12, 1927 2,353,936 Smith July 18, 1944 2,353,937 V Smith July 18, 1944 2,372,437 Lathrop Mar. 27, 1945 2,381,369 Sconce Aug. 7, 1945 2,400,719 Stackhouse May 21', 1946 

